Two-stroke internal combustion engine



Dec. 3, 1940. o. PETERSEN ET AL I I TWO-STROKE INTERNAL COMBUSTIONENGINE Filed Sept. 20, 1938 P, W g f t R 0. w 3 or 0; v g K w w a 6 MW e6 I f i 5w; i j T I i- .8 I W i J hf K v 6 Patented Dec. 3, 1940TWO-STROKE INTERNAL COMBUSTION ENGINE Ove Petersen and Einar salver,Gentofte, near Copenhagen, Denmark Application September 20, 1938,Serial No. 230,868 In Denmark September 2'7, 1937 4 Claims.

This invention relates to two-stroke stationary or marine internalcombustion compression-ignition engines having a main piston and twoexhaust pistons all operating in a common cylinder and operativelyconnected to a crank-shaft for the transmission of power thereto.

It is a primary object of the invention to to provide large internalcombustion engines of the above indicated type having pistons of equaldiameter with any desired number of cylinder units without materiallyexceeding the over-all length of corresponding engines of knownconstruction.

It is another object of the invention to provide engines of the typeabove referred to with a considerably smaller weight than the weight ofengines of known construction and having the same power output.

Still another object of the invention is to provide an engine of thetype described in which the crank-shaft is of a particularly light andrigid design thus permitting comparatively high rotating speed, and inwhich the cylinder lining and the engine frame is substantially relievedof vertical forces originating from the combustion pressures and ofstresses originating from heat distortions.

With these and other secondary objects in view the invention consists inthe novel combinations of features disclosed in the followingspecification and the annexed drawing.

In the drawing:

Fig. 1 is a vertical partial section through a double acting engineaccording to the invention with part of a connecting rod between upperand lower yokes for the exhaust pistons removed; and

Fig. 2 is a partial section taken on the line IIII of Fig. 1 and drawnto a considerably larger scale.

In the drawing, I is the main piston of the double acting engine whichpiston is connected to a crank 5 on the crank shaft 6 through a pistonrod 2, cross head 3 and connecting rod 4.

- The crank shaft 6 is mounted in main bearings I on the bed plate (notshown) of the engine.

The main piston I reciprocates in a long tubular cylinder composed oftwo cylinder portions 8 and 8, between which is inserted a shorterannular cylinder portion 9 in which the scavenging air ports it) arearranged so that the scavenging air inlet into the upper and lower endsof the cylinder is controlled by the main piston when the latter movesrespectively down below and up over the ports.

The outlet of the exhaust gases from each end of the cylinder takesplace through exhaust ports 20 and 20' respectively near the outer endsof the cylinder portions 8 and 8 and the outlet is controlled by-exhaustpistons II and I9 respectively having the same diameter as the mainpiston. The exhaust pistons are secured to an upper and a lower crossbeam I2 and I4 respectively interconnected through vertical rods I3 sothat the exhaust pistons are moved as a united assembly approximately ininverse timing relatively to the main piston but with a substantiallyshorter stroke than the latter. The exhaust pistons are connected withthe crank shaft through a pair of vertical connecting rods I5 connectedby pins IS with excentric straps I! each of which enclose one of a pairof excentrics I8 disposed on the crank shaft one at each side of thecrank 5.

In this construction the cylinder and the engine frame are entirelyreleased of Vertical combustion pressure forces.

The annular scavenging port portion 9 is provided with an outwardlydirected flange 26 serving to support the same on a shoulder on aboxshaped scavenging air manifold 23 which surrounds or encloses thescavenging port portion and part of the lower cylinder portion 8. Thescavenging air manifold 23 is supported upon a light frame 2|, 22 whichmay be made of cast iron or consist of a welded structure composed ofsteel plates and bars. The frame is supported upon the bed plate (notshown) of the engine.

The outer wall of the scavenging air manifold is extended upwards beyondthe shoulder supporting the scavenging port portion and thus between thecylinder and the scavenging air manifold is thereby formed a scavengingair space 25 which communicates with the interior space 24 of thescavenging air manifold by way of apertures in the upper Wall of themanifold.

Exhaust manifolds 21 surround the exhaust ports 20 and 20 and areconstructed in such manner that they do not prevent the upper and lowerend respectively of the cylinders from longitudinal displacements due toheat extensions. For this purpose the cylinder ends may be slidable inthe exhaust manifolds or the latter may be slidable relatively to theremaining engine frame.

We claim:

1. A double-acting two-stroke cycle stationary or marine internalcombustion compression-ignition engine having in combination, a mainpiston and two exhaust pistons opposed to and having the same diameteras the main piston but an essentially shorter stroke than the mainpiston, a common tubular cylinder provided with scavenging ports at themiddle controlled by the main piston and a set of exhaust ports in thevicinity of each open cylinder end controlled by the exhaust pistons, acrank shaft having a crank for the main piston and at either side of thesame an eccentric for transmitting the power from the exhaust piston tothe crank shaft.

2. A double-acting two-stroke cycle stationary or marine internalcombustion compression-ignition engine having, a main piston and twoexhaust pistons opposed thereto and having the same diameter as the mainpiston but an essentially shorter stroke than the main piston, a commontubular cylinder provided with scavenging ports at the middle portionand a set of exhaust ports in the vicinity of each open cylinder end,said cylinder having in the immediate vicinity of the scavenging portsan outwardly directed flange resting on and secured to supporting partsof the engine frame, the cylinder ends projecting upwardly anddownwardly respectively having only yieldable connections with fixedparts of the engine frame.

3. A double-acting two-stroke cycle stationary or marine internalcombustion compression-ignition engine having, a main piston and twoexhaust pistons opposed thereto and having the same diameter as the mainpiston but an essentially shorter stroke than the main piston, a commontubular cylinder provided with scavenging ports at the middle portionand a set of exhaust ports in the vicinity of each open cylinder end,said cylinder having in the immediate vicinity of the scavenging portsan outwardly directed flange resting on and secured to a generallyboxlike scavenging air manifold enclosing the scavenging portion of thecylinder and resting upon fixed parts of the engine frame.

4. An internal combustion engine as claimed in claim 3 in which saidcylinder is composed of a central annular portion provided with saidscavenging air ports and said supporting flange, and an upper and alower tubular portion secured thereto.

OVE PETERSEN. EINAR SQLVER.

